On its face, the gig would seem a step down for Ms. Palin, one of conservative America’s most popular and polarizing figures (not to mention major thorn in the side of the Obama White House).

But with an NBC/Wall Street Journal poll ranking a generic “Tea Party” as more popular than either Democrats or Republicans, and Palin herself rivaling the charming Mr. Obama in poll popularity, many experts see the Tea Party event as a potential milestone for a mounting, even transformational, force in US politics.

“[W]ith two wars, a continuing terror threat, huge federal deficits, and a major healthcare overhaul in the works, there is no shortage of disaffection out there … and that could prove to be political dynamite,” writes the Washington Post’s Howard Kurtz. Against that backdrop, writes Mr. Kurtz, “The tea types can either blossom into a Perotista-style third-party movement or be subsumed to some degree by the GOP.”

Can the Tea Party movement unify itself?

Indeed, the Nashville event is not about chartering a new political party to represent conservative ideals like low taxes and states’ rights, but more about unifying to take on “Obama, Pelosi and Reid this year,” writes Judson Phillips, head of Tea Party Nation, one of many Tea Party groups and the lead sponsor of a convention that will feature conservative firebrands such as Rep. Michele Bachmann (R) of Minnesota.

Already, tea-colored races are appearing around the country, including the looming matchup between Florida Gov. Charlie Crist (seen as Republican Lite by many conservatives) and Cuban-American conservative Marco Rubio, who has gotten the stamp of approval by Tea Party folks.

He says a Republican shift toward the Reaganesque Tea Party ideal could lead to a sort of pogrom for moderate Republicans, forcing out those (think Maine Sen. Olympia Snowe) who don’t hew precisely to rock-hard conservative principles around economic freedom and limited government interference.

“The Republican Party is trapped by their base, which is going increasingly conservative,” says Mr. Abramowitz. “Yes, Republicans can do fairly well in the 2010 elections – it’s entirely possible that they could pick up 20 to 30 seats in the House – but they could read the wrong message from that. In 2012, if the economy is doing reasonably well again and Obama’s popularity has stabilized, that strategy is going to be very risky and this could all come back to haunt them.”

Solidly behind that assessment, Democrats are aiming to vilify the rising Tea Party movement as woefully old-school and out of touch. “Labeling their GOP candidates as being part of the Sarah Palin or Tea Party wing of the GOP will be the key element” of Democratic attacks in 2010, writes John Fund in The Wall Street Journal.

But if the Tea Party movement stays largely independent and uses its grass-roots network to help swing contested elections, other analysts say, Democrats may want to reconsider that tack and try to tap into a movement that has quickly gone from liberal laughingstock to what New York Times columnist David Brooks grudgingly calls “a major force in American politics.”

“Looks like both grand parties will have to court the tea party supporters because many of them are independents from the purple states,” writes Ellie Velinska at RightPundits.

Now enter Palin. The former Alaska governor has already expressed her simpatico feelings for the Tea Party movement, and her high-profile presence and Facebook-touted preferences for the individual over the collective will help guarantee that eyes and ears will focus on Nashville next month.

Agreeing to appear at a major Tea Party event also gives Palin a larger platform to criticize the president and Congress, and it guarantees news coverage, potentially building momentum for a future campaign.